The disadvantage of conventional roof racks that are mountable on the roof is that the luggage or the roof box must be lifted onto the roof and fixed there. This is particularly difficult and arduous when the objects are heavy. Roof racks have therefore been suggested with devices for making it easier to convey luggage onto the roof. For example German laid-open patent application DE 41 22 823 A1 and German utility model DE 200 02 018 U1 propose roof racks with a lifting device. The disadvantage of these movable roof racks is that they possess significant additional weight and take up additional space on the roof of a motor vehicle. The air resistance and fuel consumption is thereby increased.
In a similar manner, U.S. Pat. No. 5,154,563 and DE 44 21 030 C1 disclose movable roof racks where a track system is installed on the outside of the motor vehicle that runs down from the roof or the rear or side of the motor vehicle. Roof boxes or other containers can move along this track system. This yields significantly elevated air resistance and fuel consumption in this case as well. Furthermore, the luggage containers installed on the tracks are tilted while they move so that the pieces of luggage in the luggage containers get mixed up and/or can become damaged.